Cerebrospinal fluid (CSF) surrounds your brain and spinal cord and provides a cushion to protect them from injury. The spinal cord and CSF are surrounded by three layers of membranes. A CSF leak occurs when there is a hole or tear in the outermost layer of these membranes (dura mater), which allows some of the fluid to escape.
There are two distinct types of CSF leaks with different symptoms, causes and treatments. These are spinal CSF leaks and cranial CSF leaks. A spinal CSF leak occurs anywhere in the spinal column. A cranial CSF leak occurs in the skull.
The most common symptom of a spinal CSF leak is a headache, while a cranial CSF leak causes symptoms such as clear fluid leaking from the nose or ear. Some CSF leaks may heal with conservative treatments such as bed rest. Many CSF leaks need a blood patch to cover the hole or surgery to repair the leak.
Symptoms vary between spinal and cranial CSF leaks.
Spinal CSF leaks
The most common symptom of a spinal CSF leak is headache. These headaches usually:
- Cause pain in the back of the head
- Improve when lying down
- Worsen when standing up
- May start or worsen with exertion (such as coughing or straining)
- Rarely, start suddenly ("thunderclap" headache)
Other symptoms of spinal CSF leaks may include:
- Neck or shoulder pain
- Ringing in the ears (tinnitus)
- Changes in hearing
- Nausea or vomiting
- Changes in vision
- Changes in cognition or behavior
Cranial CSF leaks
Cranial CSF leak symptoms may include:
- Clear, watery drainage from the nose or ear (on one side)
- Hearing loss
- A metallic taste in the mouth
Spinal CSF leaks may be caused by:
- A lumbar puncture (spinal tap)
- An epidural in the spine for pain relief, such as during labor and delivery
- An injury to the head or spine
- Bone spurs along the spine
- Abnormalities of the dura mater around the nerve roots in the spine
- Abnormal connections between dura mater and veins (CSF-venous fistulas)
- Prior surgery on the spine
Cranial CSF leaks may be caused by:
- A head injury
- Increased pressure in the brain
- Poorly functioning shunt
- Malformations of the inner ear
Sometimes CSF leaks develop after very minor events:
- Straining to have a bowel movement
- Lifting heavy objects
Sometimes a CSF leak doesn't have a known cause (spontaneous CSF leak).
Risk factors for spinal CSF leaks include:
- Having a previous surgery or procedure on or around the spine
- Connective tissue disorders such as Marfan syndrome or Ehlers-Danlos syndrome
Risk factors for cranial CSF leaks include:
- Having a previous surgery on or around the skull
- Obstructive sleep apnea
- Head trauma
- Tumor at the skull base
- Abnormalities of the skull base or inner ear
Possible complications of a cranial CSF leak that is left untreated include meningitis and air entering the spaces surrounding the brain (tension pneumocephalus).
CSF leak (Cerebrospinal fluid leak) care at Mayo Clinic
Oct. 26, 2021
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CSF leak (Cerebrospinal fluid leak)